The Complete Guide for MongoDB Migration

Published 2020-07-24

This post documented down all steps required to migrate your MongoDB to a new machine. At the end of this article, you will have a MongoDB with identical collections and documents compared to the previous machine. Without further ado, let's start.

Problem Statement

It happened that I need to switch my development machine and I would need to migrate the data in my local MongoDB to the new machine.

Primary Objectives

  • Avoid Wasting Time and Effort to Re-create Dummy Data in MongoDB. My projects are having 7-8 microservices and databases, each microservice has about 2-3 collections. Thus, I couldn't imagine if I am going to re-create those data.

Although my problem is specifically for data migration for the development machine, but I believe this article could help you as long as you're performing migration for MongoDB.

Solution Analysis

The moment when I knew that I need to do this migration, I am a bit panicked as I have zero experience in doing MongoDB migration. It's important to remain calm (sometimes I couldn't) and resolves the problem bit by bit. I break this down into two parts:

  • Backup the MongoDB data.
  • Restore the data into the new machine.

Backup MongoDB Data

We can use mongodump command to backup our own database. Open your terminal and run the following command you will be able to generate the dump file.

mongodump --host localhost:27017 --username USERNAME --password PASSWORD --authenticationDatabase admin --out ~/Desktop/mongo-migration

I used the above command to backup all the database in the MongoDB. Below are the detail of the mongodump options:

  • --host - Default value: localhost:27017. I declared explicitly here is to allow things to be clearer and better understanding towards each option.
  • --username - Username used for authentication of MongoDB or Specific Database.
  • --password - Password used for authentication of MongoDB or Specific Database.
  • --out - The file directory where you want to save your dump file. By default, it saved under dump directory which located on the current directory.

Here is the output of my dump files. Refer to the screenshot below and each folder represent a DB.

Screenshot 2020-07-22 at 10.29.00 PM

Restore MongoDB Data

At this stage, you already have your dump files directory in your new machine. Next, we can proceed to restore the MongoDB data.

Let's assume I saved my dump directory at this path ~/Downloads/mongo-migration.

Now we can use the default root role we have in MongoDB to restore the database. Refer to the command below.

We can use this single command to restore all the database and you would have the exact same database like previously

mongorestore ~/Downloads/mongo-migration/ -u root --host 127.0.0.1:27017 --authenticationDatabase admin

Restore Mutiple DB

However, there could be a scenario where you only want to restore a few DBs and excluding a few DBs from the dump directory.

For e.g, I want to restore audit and client table at this round. We can do this using --nsInclude and nsExclude option in mongorestore.

Example of using --nsInclude

We can use --nsInclude to select only the database and collections that we want to restore. In the command below, we restore all the collections in the audit database using audit.* and all collections in the client database using client.*.

The wildcard after the dot notation means all collections in the database. If you want to include or exclude multiple databases, you would need to specify it nsInclude or nsExclude. Refer to the example below.

mongorestore ~/Downloads/mongo-migration/ -u root --host 127.0.0.1:27017 --authenticationDatabase admin --nsInclude="audit.*" --nsInclude="client.*"

Example of using --nsExclude

We can use nsExclude to exclude the database and collections that we do not want to restore. In the command below, we exclude partner, promotions, transaction and utilities database.

mongorestore ~/Downloads/mongo-migration/ -u root --host 127.0.0.1:27017 --authenticationDatabase admin --nsExclude="partner.*" --nsExclude="promotions.*" --nsExclude="transaction.*" --nsExclude="utilities.*"

Restore Single DB

Lastly, this is the command to restore the single DB. Few things to take note here:

  • -d options - Specify the database name to be restored. This is a REQUIRED option.
  • Specify the correct dump directory. For e.,g, if I am restoring utilities database, I must specify the utilities database dump directory.

Refer to the command below.

mongorestore -d utilities ~/Downloads/mongo-migration/utilities -u root --host 127.0.0.1:27017 --authenticationDatabase admin

Conclusion

Here are the key points of this article.

  • Discussed the details on how to backup the MongoDB using mongodump.
  • Discussed the details on how to restore all database, multiple databases and single database using mongorestore

Thank you for reading. See you in the next article.

References